As a punishment for something naughty that we did, my little brother and I have to whitewash both sides of a fence. We start at the same time, and we each work at a constant rate. If we each whitewash one side, I'll finish in 2 hours and my brother will finish in 3 hours. But I'm a nice kid, so after I finish my side, I go around to the other side and help my brother finish his side. From the time I start helping him, how many minutes does it take us to finish the job?
+128474 As a punishment for something naughty that we did, my little brother and I have to whitewash both sides of a fence. We start at the same time, and we each work at a constant rate. If we each whitewash one side, I'll finish in 2 hours and my brother will finish in 3 hours. But I'm a nice kid, so after I finish my side, I go around to the other side and help my brother finish his side. From the time I start helping him, how many minutes does it take us to finish the job?
Well....you can paint 1/2 of the fence on your side in one hour and your brother can paint 1/3 of the fence on his side in one hour.....so...together......you both can paint (1/2) + (1/3) = 5/6 of the fence on either side in one hour
So....after 2 hours......your brother has painted 2 (1/3) = 2/3 of the fence on his side and there is 1/3 left to paint
So
Work left / Rate Per Hour = Time to finish
(1/3) / (5/6) =
(1/3) (6/5) =
6/15 hrs =
2/5 hrs =
24 minutes
P.S. - have you and your brother ever read "Tom Sawyer??"
